"THE SOURCE PLASMA OF SOLAR ENERGETIC PARTICLES IN GRADUAL EVENTS"

P.R. Boberg, A.J. Tylka, and J.H. Adams, Jr.

In recent years, the wealth of evidence has indicated that large solar energetic particle (SEP) events are caused by CME driven shocks. In this scenario, the interplanetary source population is considered to be the local plasma encountered by the shock[1], e.g. the solar wind on field lines which are well connected to the observer. The recent high-energy (E = ~200 - 600 MeV/nuc) SEP Fe mean charge state ( = 14.2 +/- 1.4) result[2] during September-October 1989 is inconsistent with a typical solar wind charge state distribution, and indicates that is essentially unchanged from ~1 MeV/nuc[3,4]. We explore alternative scenarios and discuss related measurements.

[1] Reames, D.V., Adv. Space Res., 15 (1995) (7)41. [2] Tylka, A.J., et al., Ap.J., 444 (1995) L109. [3] Luhn, A. et al., Proc. 19th ICRC (La Jolla), 4 (1985) 241. [4] Luhn, A. et al., Ap.J., 317 (1987) 951.